docs: add note about the CSR feature

Related: socketio/socket.io#4733

Author: darrachequesne

docs/categories/01-Documentation/connection-state-recovery.md

@@ -4,7 +4,15 @@ sidebar_position: 4
 slug: /connection-state-recovery
 ---
 
-Connection state recovery is a feature which allows restoring a client's state after a temporary disconnection (including any missed packets).
+Connection state recovery is a feature which allows restoring a client's state after a temporary disconnection, including any missed packets.
+
+:::info
+
+This feature was added in version `4.6.0`, released in February 2023.
+
+The release notes can be found [here](../../changelog/4.6.0.md).
+
+:::
 
 ## Disclaimer
 
@@ -111,6 +119,12 @@ foo       => the event name (socket.emit("foo"))
 MzUPkW0   => the offset
 ```
 
+:::note
+
+For the recovery to succeed, the server must send at least one event, in order to initialize the offset on the client side.
+
+:::
+
 - upon temporary disconnection, the server stores the client state for a given delay (implemented at the adapter level)
 
 - upon reconnection, the client sends both the session ID and the last offset it has processed, and the server tries to restore the state